Use Devicetree to describe the radio and IEEE 802.15.4. This allows to
remove usage of IEEE802154_CC13XX_CC26XX_DRV_NAME in preparation for the
removal of NET_CONFIG_IEEE802154_DEV_NAME. All boards used in testing
have been updated to enable the peripheral in DT as well.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
